The present invention is directed to affixing substrates to heat transferring devices. The present invention is especially directed to affixing substrates to heat transferring devices when the affixed substrates have power dissipating (i.e., heat generating) components. The present invention affixes circuit-bearing substrates to heat transferring devices in a structure permitting occupation of a larger portion of the substrate surface facing the heat transferring device in an assembled orientation than has heretofore been feasible using prior art circuit-bearing substrates.
In today's market manufacturers are pressured to offer power conversion products handling increased power in a smaller package size. One result of these market pressures is that board space on surfaces of circuit-bearing substrates is at a premium. Increased power requires greater heat transfer from products in order to maintain reliability and product life.
A technique for transferring heat from a product is to attach a heat transfer device, such as a heat sink, in proximity with heat generating circuitry to aid in transferring heat away from the heat source. Spacing between the heat transferring device and adjacent circuitry is an important consideration. A product designer provides spacing to establish a small separation to facilitate heat transfer away from the circuitry. However, the spacing must not be so close as to provide an arc path or conduction path from the circuitry. Prior art heat transfer device affixing systems and apparatuses have relied upon a spacing structure such as a stepped section or shoulder in a support post to abut a face of a circuit-bearing substrate facing the mounted heat transferring device when assembled. Often a grounding pad structure is provided on the face of the substrate to contact the shoulder and thereby electrically grounding the heat transferring device. A disadvantage of such a structure is that the shoulder and the grounding pad occupy valuable substrate space that could otherwise be employed for implementing circuitry.
There is a need for a system and apparatus for fixing a substrate with a heat transferring device that does not occupy surface area of the substrate.